The invention applies more specifically, but not exclusively, to guiding devices for tension members, such as strands of cables which, made up of a multiplicity of strands, are used in civil engineering and building activities.
Numerous structures and notably bridges comprise cables which are used in particular to support elements of these structures. Such cables are stressed in traction between their opposite ends, but frequently saddles, also known as guiding devices, are used for holding the cables in such a manner as to deviate them in whatever way in the direction in which they must extend.
The function of a saddle of the type cited above is thus to permit lateral and/or longitudinal and local holding of a cable and transfer of the stress caused by this deviation to a support, such as a bridge pylori, provided for this purpose. A saddle of the aforementioned type is intended to be interposed between the support and the cable such as inside a pylori for stay cables or a bridge girder diaphragm for external tendons. Conventional saddles used one simple steel pipe for all strands, i.e. the bundle of strands placed inside one common pipe. In some solutions individual steel tubes were provided for the strands. More recently, saddles with holes or channels (obtained by so-called void formers which are removed after the grouting) for each individual strand were developed. In some solutions these holes have a V shape to improve the clamping effect. Saddles with individual tubes or channels are conceived to allow individual local support of each strand of a cable.
To this end, a recent saddle comprises at least one bearing area for guiding a strand of a cable, and preferably a plurality of bearing areas for deviation, each permitting the individual support of one of the strands of a cable.
In known saddle solutions, the saddle is composed of a round or rectangular or otherwise shaped steel box filled, after strand installation, with a high-strength cement grout. Strands are arranged to traverse the saddle longitudinally inside the rectangular steel box. In such solutions, the strands can be unsheathed to increase friction between the strands and some parts of the saddle. In the case of fully grouted and bonded strands, the cement mortar can also protect the unsheathed strands from corrosion. However, the disadvantage in this case is that the strands are tightly in place in the solidified cement mortar, and for this reason the strands cannot be replaced individually. In the context of this application, the term corrosion is used to mean any process, for example chemical or electrolytic, which can have a deleterious effect on the chemical integrity, and hence the mechanical properties, of the strands.
It is also possible to insert in the saddle curved tubes or channels for holding the strands in place in the saddle. The saddle conventionally comprises at least as many tubes as the guide cable, also known as the stay cable, comprises strands. Each strand is then arranged to traverse one tube longitudinally. This solution does not require subsequently filling the saddle with cement mortar. An advantage of this solution is that it allows the replacing of the strands individually. A disadvantage of this solution is, however, that the tubes and strands are susceptible to corrosion.
It is the aim of the present invention to provide an improved saddle concept so that the shortcomings of the prior art can be overcome.